Med diet cuts breast cancer risk in older women, says study

Adherence to a Mediterranean diet along with avoidance of Western-type foods may contribute to a reduction in postmenopausal breast cancer risk, claims new French study.

According to findings published in this month’s American Journal of Epidemiology, the incidence of breast cancer may be lowered in postmenopausal women by a diet comprising mostly fruits, vegetables, fish and olive/sunflower oil.

The researchers maintain that up to now evidence for associations between breast cancer risk and specific foods or nutrients has been limited, except for alcohol.

Breast cancer incidence varies widely between countries, claims the study, and the researchers add that this suggests the influence of environmental factors:

“The Japanese have traditionally been at low risk of breast cancer but breast cancer incidence in Japan has recently increased concomitantly with major changes in traditional habits, especially diet.

“The increasing incidence of breast cancer in Japan can be attributed at least partly to the adoption of a Western diet, which is notably characterized by higher intakes of meat, dairy products, and saturated fat, and decreased consumption of traditional Japanese foods such as seafood products,” continued the scientists.

Method

The scientists report that research was initiated in 1990 and involved 65,374 women living in France who were born between 1925 and 1950, with participants completing biennial self-administered follow-up questionnaires on health status, medical history, and lifestyle.

Dietary data was collected via a self-administered diet history questionnaire assessing consumption of 208 foods and beverages, states the article.

The scientists said that they considered potential interactions with known risk factors for breast cancer such as age, educational level, geographic area at baseline, body mass index, height, family history of breast cancer, pregnancy and breastfeeding history and current use of vitamin/mineral supplements.

Scores for dietary patterns were obtained by factor analysis, and breast cancer hazard ratios were estimated by Cox proportional hazards regression for the highest quartile of dietary pattern score versus the lowest.

Results

The report states that among the women studied, 2,381 developed postmenopausal invasive breast cancer during a median follow-up period of 9.7 years.

The researchers said that their findings indicate that a Mediterranean diet is associated with a reduced risk of breast cancer only if energy intake remains within recommendations and if ‘unhealthy’ foods are not consumed in large quantities.

However, they stress that it was difficult to determine which components of the Mediterranean pattern explain the inverse association with breast cancer risk.

The risk associated with the 'alcohol/Western' eating pattern was higher in the case of tumours that were estrogen receptor-positive/progesterone receptor-negative, added the researchers.